Apparatus and system to remove debris from a laser-extended bore section

ABSTRACT

An apparatus and a system to remove debris generated by using laser light to extend a bore section comprises a body connected to an umbilical and a plurality of coolant injection ports arranged about an inlet to a debris removal passage through the body. The umbilical is used to position the body adjacent a bore wall in a bore section to be extended, laser light is emitted from the apparatus to melt at least a component of a formation material in which the bore is to be extended and to generate globules of melted formation components. A gas is injected into the bore section to disrupt and to sweep at least some of the molten material from a laser path into the debris removal passage as an injected stream of coolant within the passage intercepts the remnants of globules of molten material as they accelerate in the debris removal passage.

STATEMENT OF RELATED APPLICATIONS

This application depends from and claims priority to International PCT/US2012/046503 filed on Jul. 12, 2012, which claims priority to Hungarian Application No. P1100383 filed on Jul. 15, 2011.

BACKGROUND

1. Field of Invention

The present invention relates to the drilling of earthen bores to recover fluids residing in subterranean geologic formations. More specifically, the present invention relates to the removal of debris from a bore section extended into a geologic formation using a laser drilling process.

2. Background of the Related Art

Borehole systems are drilled into the earth's crust to penetrate subsurface geologic formations bearing a fluid, such as water, oil or gas, to facilitate the production of the formation fluid to the surface. A bore system may comprise a single bore surrounded by a bore wall or, alternately, a primary bore having one or more intersecting lateral bores surrounded, along with the primary bore, by a bore wall.

A bore system may be bored in the earth's crust using conventional mechanical drilling rigs at the earth's surface to rotate a drill bit at a leading end of a drill string extending from the rig. Some rigs rotate the entire drill string, which may comprise a plurality of segments or stands of drill pipe threadedly coupled to form an elongate drill string. The drill string can be made up by adding segments as the drill string is extended deeper into the earth's crust or laid down by removing segments as the drill string is withdrawn from the earth's crust. The rotation of the drill string and the drill bit at the leading end of the drill string, while urging the drill bit against an end of a primary bore or lateral bore section to be extended to break apart rock engaged by the drill bit.

Alternately, a drill string may comprise a mud motor proximal to the leading end and hydraulically powered by fluid provided through the center of the drill string to rotate a drill bit coupled to the mud motor to break apart the rock engaged by the drill bit. With a mud motor or a conventional drill string, drill cuttings are removed from the portion of the bore to be extended by circulating working fluid down the drill string and back to the earth's surface through the annulus between the drill string and the wall of the bore.

Other methods for extending a section bore system include the use of laser light to heat and melt at least some components of the geologic formation exposed to a laser path adjacent to a laser drill head connected to a leading end of a drill string. A laser drilling process may include the removal of debris resulting from the drilling process by circulating a carrier fluid into and from the section of the bore system being extended using the drill head. A laser path between the drill head and a portion of the bore wall to be extended is irradiated using the drill head. The laser path must first be cleared of laser-obstructing materials so that the laser light emitted from the drill head can impinge on the targeted portion of the wall to be irradiated by the laser.

Still other systems and methods for extending a section of a bore system include the use of a high-pressure jet to mechanically fracture rock within a fluid path adjacent to a liquid jet at the leading end of a drill string. High-pressure jet drilling may include the removal of debris resulting from the drilling process by circulating fluid into and from the portion of the borehole system being extended. For best results, the jet path between the liquid jet and the portion of the bore wall to be jet blasted should be as short as possible to impart a maximum amount of liquid kinetic energy on the portion of the wall to be jet blasted.

Each of the above-described processes generate debris resulting from the removal of formation material as a bore section is extended. Conventional methods of extending bore sections rely on circulation of working fluid or drilling fluid to suspend and remove rock bits and fragments from the bore system. At the surface, the suspended rock bits and fragments, or drill cuttings, are removed from the working fluid by introducing the drilling fluid into a pit where the fluid is motionless or nearly motionless to allow density separation of the heavier drill cuttings from the relatively lighter working fluid. Apparatuses such as shale shakers and screens can also be utilized to remove drill cuttings.

BRIEF SUMMARY OF THE INVENTION

An embodiment of the present invention provides an apparatus and a system to remove debris generated by a laser drilling process in which globules of melted formation material are favorably broken apart and shaped by a gas stream and then frozen in situ prior to removal. The breaking apart and shaping of molten globules of formation material is obtained by imposing aerodynamic forces on globules of melted formation material as they are swept from the targeted portion of the bore wall irradiated by laser light. The broken and shaped globules are then frozen using a curtain or barrier of fluid coolant to form solid, shaped particles and pieces of debris. The process provides debris in sufficiently small portions with a shape that enables the particles and pieces to be transported within a fluid stream to a debris receiver at the surface.

For example, but not by way of limitation, a globule of molten formation material may have a generally spherical or a generally ellipsoidal shape due to viscoelastic forces such as, for example, surface tension. The shape of a globule of molten formation material is disturbed as a gas stream injected into the laser path sweeps the globule from the laser path and to a debris removal channel maintained at a pressure lower than the pressure of the injected stream gas. According to principles of material transport technology, a globule swept from a bore wall would be difficult to transport from the bore section using the gas flow stream because of a generally low surface area-to-weight ratio that resists suspension and movement. The amount of force that may be applied by moving gas to a globule of melted formation material, or to a frozen piece of formation material, is limited by the compact, dense configuration. As a result, removal of debris from a bore section extended using a laser drilling process is difficult to accomplish using a stream of low density gas.

The present invention provides an apparatus and a system to remove debris generated by a laser-drilling process from an earthen bore section using a low-density gas stream that includes the steps of breaking apart and shaping the globule to dramatically increase the surface area to weight ratio and to elongate and/or flatten the broken apart portions to increase surface area further, and by then injecting a coolant to freeze the broken and shaped remnants of the globule in the modified shape. The resulting remnants, once frozen, retain the shape and have a favorable surface area-to-weight ratio for being transported from the bore section to the surface within a moving gas flow stream.

The extent to which the breaking apart, shaping and then freezing of melted formation material conditions the material for being favorably transported to the surface within a gas stream depends, at least in part, on the chemical composition of the formation into which the bore section is being extended and on the propensity of the material to break apart and to form flattened or elongate pieces, resembling platelets or fibers, when subjected to the shaping flow of a gas stream entering a mouth of a debris removal channel in a drill head. If the geologic formation is of a material having a high content of a component that melts in response to heating by laser light, the material will be favorably shaped into small bits that can be frozen to form solid platelets or fibers that are suitable for being transported within a moving stream of gas withdrawn from the bore section through an umbilical having a debris removal channel. As a result, the efficiency of the inventive apparatus and system depends at least in part on the chemical composition of the formation into which the bore section is extended. For example, some geologic formations, such as sandstone, comprise a substantial amount of silica, a material that can be melted and favorably removed from the bore section using the system and apparatus of the present invention.

Unlike conventional drilling processes, however, a laser drilling process is more sensitive to the material in the bore section to be extended. In order to use the apparatus and system of the present invention, the immediate bore section to be extended must be conditioned for the use of a laser-powered drill head. The drill head emits laser light that is directed through a laser path onto a portion of the bore wall to be removed to extend the bore section. Laser-obstructing materials such as, for example, drilling mud and, in some cases, denser formation fluids that have migrated into the bore section are displaced from the laser path intermediate the drill head and the bore wall by isolating the portion of the bore section to be extended using a deployable annular seal and by then injecting a laser-conductive material, such as an inert or other non-reactive gas, from the drill head and into the portion of the bore section to be extended. The laser-conductive material displaces laser-obstructing material(s) from the laser path to facilitate the unimpaired transmission of laser light from the drill head to the targeted portion of the bore wall.

The formation materials that make up the bore wall are heated by impingement of the laser light emitted from the drill head, and globules of melted formation materials are formed and then swept from the bore wall by continued injection of the laser conductive material, or gas. Depending on the composition of the formation and fluid residing therein, some components of the formation may vaporize within the bore section, but most solid components will either burn or melt.

Formation components that melt are swept from the bore wall by the injected gas stream and form globules of molten material. Molten components of the formation form globules having a substantial volume, as compared to much smaller drops. This physical liquid state of the melted formation components is formed due to unbalanced intermolecular viscoelastic forces acting at and on the exterior surface of each globule, as a result of which the surface layer tends to contract and exhibit properties resembling a stretched elastic membrane. This physical phenomenon relating to the viscoelasticity of laser-molten formation components provides an opportunity to strategically manipulate the globules as they are generated in the irradiated bore section to facilitate the removal of the material to the surface.

Globules of a molten formation component can be dynamically shaped; that is, that they can be advantageously shaped by subjecting the molten components to acceleration. In one embodiment of the present invention, globules resulting from the extension of a bore section are shaped and conditioned to promote removal from the bore section using an umbilical having an elongate debris removal channel. A leading end of the umbilical is connected to a drill head through which laser light and injected gas can be delivered from the surface to the section of bore to be extended. The umbilical provides a debris removal channel through which debris and globules, or the remnants thereof, can be transported from the bore section to the surface.

As formation components are melted and swept from the targeted bore wall as globules of molten material, a pressure differential is maintained to move the injected laser conductive material, or gas, from the bore section being extended into and through the debris removal channel. The laser conductive material (gas) delivered from the surface to the drill head through the umbilical is injected into the bore section being extended to sweep debris from the irradiated bore wall and to provide a source of pressure. The pressure builds up in the bore section thereby creating a pressure differential into the debris removal channel in the umbilical. The pressure differential causes laser conductive material (gas) and molten formation globules and debris to be swept into the mouth of the debris removal channel in the drill head. The debris removal channel facilitates the shaping and freezing of the matter entrained in the stream of laser conductive material (gas) and the transport of the material to the surface via the debris removal channel in the umbilical. The transported material is delivered to a debris receiver connected to the surface end of the debris removal channel. In one embodiment, the debris receiver is a vessel having an outlet, generally near the top, for removal of gases.

One embodiment of the apparatus and system of the present invention enables molten debris to be broken apart, shaped and then frozen or otherwise stabilized to prevent unwanted adherence of formation components and debris to an interior wall of the debris removal channel. As molten globules near the mouth of the debris removal passage in the drill head, a globule of molten material accelerates due to frictional forces applied by the laser conducting material (gas) stream entering the debris removal channel as compelled by the pressure differential. Accelerating laser conductive material (gas) rushes past globules of molten debris entrained within the stream to cause the globules to substantially flatten, elongate and break apart due to frictional forces acting on the exterior of each globule and inertia forces resisting acceleration. The substantially more dense globules tend to resist acceleration forces imparted to the globule by the friction of the substantially less dense surrounding stream of laser conductive material (gas). The globules become flattened, extended and/or elongated by these opposing forces as they accelerate the globule, and the externally applied forces overcome the intermolecular viscoelastic forces at the surface layers that tend to otherwise retain the globule in a spherical or ellipsoidal (compact) shape.

One embodiment of the apparatus and system enables the remnants of a broken globule of molten formation components to be quick-frozen using a curtain or barrier of coolant positioned at or proximal to the mouth of the debris removal passage of the drill head at which the globule experiences a peak rate of acceleration. In one embodiment of the system, the coolant comprises a gas which, when introduced at very high pressures (>100 bar), readily quenches and freezes molten globules of formation material into elongate or flattened solid bits and particles. In one embodiment of the system, the coolant is the same laser-conductive gas used to displace laser-obstructing materials from the laser path and the same gas used to displace laser obstructing materials and to sweep molten debris from the bore wall.

In another embodiment of the system, the coolant is a highly conductive liquid suitable for maximizing heat transfer from the molten formation material to the liquid. For example, the highly conductive liquid coolant may be water, potassium chloride, deionized water, inhibited glycol and water solutions, or dielectric fluids injected through one or more coolant injection ports formed in or connected to or near the mouth of the debris removal channel to form a curtain or barrier of injected coolant through which the molten remnants of the globules pass to enter the debris removal channel of the umbilical.

In one embodiment of the system, a plurality of coolant injection ports are positioned in a generally circular pattern about the mouth of the debris removal passage to together provide a curtain or barrier through which the stream of laser conductive material (gas), and the debris entrained therein, must pass to enter the debris removal channel of the umbilical for transport to the surface. In a related embodiment of the system, a plurality of coolant injection ports are adapted to emit a broad stream of coolant which may intersect with similarly shaped streams of coolant provided from adjacent coolant injection ports to form the curtain of coolant. In a related embodiment, the coolant injection ports are angularly distributed about the mouth of the debris removal channel and angled to inject coolant streams generally away from the bore wall and generally into the debris removal passage of the drill head. In one embodiment, a secondary set of coolant injection ports may be provided within the body and positioned to provide an auxiliary protective curtain or sleeve of coolant directed longitudinally along the interior wall of the debris removal passage.

In addition, a suitable material is selected for the debris removal passage, or for the interior wall of the debris removal passage, to impair adherence of formation components and debris to the debris removal passage. For example, but not by way of limitation, the interior wall of the debris removal passage in the drill head that feeds laser conductive material (gas) and debris into the debris removal channel of the umbilical may comprise or be lined with an aluminum, aluminum alloy, steel or steel alloy material that forms a stable oxidized layer or a layer that is generally both physically and chemically non-reactive, even at elevated temperatures. Alternately, the interior wall of the debris removal passage may comprise a ceramic or other non-reactive material. In one embodiment the interior walls of the debris removal passage may be lined with non-sticking material such as, for example, Teflon®, or the interior wall may be conditioned or treated to resist adherence of materials that enter the debris removal passage.

In one embodiment of the apparatus and system, a second set of coolant injection ports may be positioned within the body or drill head to provide a secondary layer of protection against melted formation components or bits of debris adhering along the interior wall of the debris removal channel of the drill head. A secondary set of coolant injection ports may together provide a secondary sleeve or curtain of coolant to protect the interior wall of the debris removal channel from accumulating molten formation components or debris emerging from an encounter with the primary curtain with sufficient retained heat to promote unwanted adherence to the interior wall. The secondary set of coolant injection ports may, like the primary set of coolant injection ports, inject the laser conductive material as the coolant or a liquid coolant.

BRIEF DESCRIPTION OF THE SEVERAL. VIEWS OF THE DRAWINGS

FIG. 1 is a schematic illustrating a system of the present invention.

FIG. 2 is an enlarged perspective view of an alternative spool that can be used to store an umbilical of a system of the present invention.

FIG. 3 is an enlarged top view of a second alternative spool that can be used to store an umbilical of a system of the present invention.

FIG. 4 is a perspective view of a portion of an embodiment of an apparatus, a drill head, which can be used to implement one embodiment of the system of the present invention.

FIG. 5 is an enlarged partial section view of the drill head of FIG. 4.

FIG. 6 is a section view of an alternative debris removal channel having both a primary set and a secondary set of coolant injection ports to freeze molten formation components and to stabilize heated debris.

FIG. 7 is an illustration of one mode of globule deformation that may occur as a globule of molten formation components entrained within an accelerated gas stream entering a debris removal passage of a drill head.

FIG. 8 is a view of an arrangement of coolant injection ports, secondary coolant injection ports, debris removal passage mouth and optical elements an alternative embodiment of a body that can be positioned using an umbilical in an embodiment of a system and apparatus of the present invention.

FIG. 9 is an elevation view of a portion of a bore system comprising a single lateral bore intersecting a primary bore at a window in a casing installed within the primary bore.

FIG. 10 is an elevation view of the portion of the bore system of FIG. 9 with a guide tool disposed in the primary bore to guide the drill head through the casing window into the lateral bore to extend the lateral bore.

DETAILED DESCRIPTION

One embodiment of the present invention provides an apparatus and system to extend a bore section comprising an elongate umbilical for positioning a drill head connected to a leading end of the umbilical within a bore section of an earthen bore system. The umbilical includes a debris removal channel, a gas conduit to supply a laser conductive gas to the bore section, and a plurality of optically transmitting fibers to supply laser light to the drill head. One embodiment of the apparatus and system, the umbilical includes a coolant conduit to deliver fluidic coolant to the drill head. In other embodiments, the laser conductive gas supplied to the drill head through the gas conduit of the umbilical also serves as a coolant.

In one embodiment, the umbilical is stored on and fed into an earthen bore system from a reel, a spool or other storage device. The storage device on which the umbilical may be wound or coiled facilitates transportation of the umbilical to and from the surface location of the bore system. The storage device may be rotated in a first direction to feed the umbilical into a bore system and position the drill head coupled to the leading end of the umbilical, and the storage device may be rotated in a reversed direction to retrieve the umbilical from the bore system and back onto the storage device.

The storage device may be connected to a rotatable fluid coupling that is coupled to a surface end of the gas conduit of the umbilical to facilitate the flow of gas from a pressurized gas source at the earth's surface to a surface end of the gas conduit. The pressurized gas is delivered through the gas conduit to the drill head connected to the leading end of the gas conduit. In embodiments of the umbilical having a coolant conduit in addition to a gas conduit, the umbilical storage device may be connected to a second rotatable fluid coupling that receives coolant from a coolant storage device on the surface connected to a surface end of the coolant conduit. The coolant is delivered through the coolant conduit to the drill head.

Similarly, the storage device may be connected to a rotatable optical transmission coupling connected to a surface end of the optical fibers of the umbilical to facilitate the transmission of laser light from a laser generator on the earth's surface to a surface end of the optically transmitting fibers of the umbilical. The laser light is transmitted through the optical fibers of the umbilical to optical elements in the drill head connected to the leading end of the umbilical. The rotatable couplings may be connected to and used with the umbilical storage device to accommodate rotary movement of the umbilical storage device relative to the earth's surface while providing a continuous supply of gas, laser light and coolant without unwanted twisting or binding of the umbilical. Alternately, the laser generator may be disposed within the center of the spool about which the umbilical is wound or coiled.

The umbilical comprises a leading end, to which the drill head is connected, for being introduced into the bore system. The umbilical storage device rotates to feed out the umbilical into the bore system in an amount sufficient to position the drill head at the leading end of the umbilical proximal a portion of a bore wall at the end of a bore section to be extended using the drill head. The drill head comprises one or more gas injection ports to introduce gas supplied through the gas conduit of the umbilical to displace laser obstructing materials from a laser path intermediate the drill head and a targeted portion of the bore wall. Laser obstructing materials may include, but are not limited to, working fluid, drilling fluid, formation fluids and other fluids and debris. The drill head is provided with a deployable circumferential seal intermediate the emitting end and the connected end to circumferentially deploy and engage the bore wall to isolate a portion of the bore section to be extended from the remainder of the bore system. The laser path, as that term is used herein, is the path through which the laser light emitted from the emitting end of the drill head will beam to impinge on the targeted portion of the wall of the bore section to be extended using the drill head.

The drill head may further comprise one or more optical elements coupled to an emitting end of the drill head to focus and condition the laser light transmitted from the surface. The optical elements may focus or condition the laser light for optimal heating of the targeted portion of the bore wall. The optical elements may comprise lenses housed at the emitting end of the drill head and optically coupled to a leading end of optical fibers extending from the umbilical and terminating at or within the drill head. The optical elements may be housed, for example, at an end of the drill head generally opposite the connected end of the drill head, and the optical elements may be protected using a transparent protective member through which emitted laser light may pass to impinge upon the targeted portion of the bore wall opposite the laser path from the emitting end of the drill head.

In embodiments using the gas supplied to the drill head as a coolant, a valve may be disposed to provide a split stream of the gas from the gas conduit to coolant injection ports arranged to introduce streams of coolant into the debris removal passage of the drill head. On one embodiment, a plurality of coolant injection ports may be angularly distributed about, within or proximal to a mouth of the debris removal passage of the drill head to provide coolant streams together forming a curtain or barrier of coolant through which molten formation components swept into the debris removal passage must pass to enter the leading end of the debris removal channel of the umbilical.

For example, but not by way of limitation, a set of four coolant injection ports may be distributed at 90 degree (1.57 radians) intervals about the mouth of the debris removal passage of the drill head. The coolant injection ports may be oriented to introduce four generally broad streams of coolant into the debris removal passage. The four streams intersect one with the others to form a curtain of coolant within a throat of the debris removal passage of the drill head. As molten formation components and other heated debris are swept into the debris removal passage by laser conductive materials (gas) injected into the bore section, the curtain of coolant freezes the molten formation components, and cools and stabilizes the heated debris, to prevent adherence of these materials to the interior wall of the debris removal passage or to the interior wall of the debris removal channel of the umbilical.

In one embodiment, the deployable circumferential seal on the drill head is an inflatable member, and the deployment of the seal may be implemented by remotely opening a valve fluidically coupled between one of the coolant conduit (if available) and the gas conduit, on a source side of the valve, and the seal, on the receiving side of the valve, to inflate and deploy the seal using gas or coolant provided through the gas conduit or coolant conduit, respectively. In one embodiment, the deployed seal may be retracted from the deployed configuration by closing the valve supplying the gas or coolant and by then remotely opening a second valve coupled to release the coolant or gas from the inflated seal to the bore section. In another embodiment, the valve coupled to selectively introduce coolant or gas from the coolant conduit or gas conduit to the seal to inflate the seal and the second valve coupled to selectively release coolant or gas from the seal to the bore may be replaced with a single remotely-controllable three-way valve having a first selectable position to establish communication between the coolant conduit or gas conduit and the seal to inflate the seal and a second selectable position to establish communication between the inflated seal and the bore section.

The above-described system of the present invention comprise a body, also referred to herein as a drill head, an umbilical, and umbilical storage device, a pressurized gas source, and an optional coolant source (in embodiments not using a gas as the coolant), may be used to extend a bore section of a bore system, and to remove from the extended bore section debris generated by use of a laser drill head. Melted formation components and heated debris are swept into a debris removal passage of the body to engage the curtain or barrier of coolant provided by one or more coolant injection ports.

The apparatus and system of the present invention enables the breaking apart, shaping and stabilization of molten formation components and heated debris generated by the laser drilling process. Molten formation components are exposed to an accelerating gas stream that surrounds and sweeps globules of molten formation components into a debris removal passage in a drill head. The physical interaction between the accelerating gas stream and a globule of molten formation component is similar to a droplet of a liquid, such as water, accelerating into a much less dense gas, such as air. A globule of molten formation component is destabilized similar to the Rayleigh-Taylor instability observed when a heavy liquid accelerates into a substantially less dense gas. The increasing friction or drag associated with the accelerating gas stream causes the globule to initially flatten or elongate, and then to aerodynamically break apart into multiple smaller drops or globules as the viscoelastic forces that maintain the molten formation components as a unitary globule are overcome by the rapidly increasing and disruptive aerodynamic forces imparted by the surrounding gas stream. The apparatus and system of the present invention use this phenomenon to aerodynamically break up globules of molten formation components generated by the laser drilling process into very small droplets of molten formation components that can be advantageously frozen by engagement with a curtain of coolant strategically positioned within the debris removal passage to engage the remnants of the globules, i.e. the broken apart droplets of molten formation components, immediately after they are formed by the accelerating gas stream.

Freezing of the droplets of melted formation components and cooling of debris from the laser drilling process prevents adherence of these materials to the interior wall of the debris removal passage of the body and, subsequently, to the interior wall of the debris removal channel of the umbilical. In one embodiment, the body further comprises a secondary set of coolant injection ports providing set of coolant streams directed along the interior wall of the debris removal passage of the body. The secondary set of coolant injection ports provide an additional measure of protection against molten formation components or heated debris that passes through a primary curtain or barrier of coolant provided by the primary or first set of coolant injection ports.

Preferably, the coolant is a highly conductive material having a substantial specific heat to provide maximum heat transfer from the melted formation components and heated debris to the coolant curtain. In one embodiment, the coolant is liquid, such as water. In another embodiment, the coolant is potassium chloride or an inhibited glycol solution. In another embodiment, the coolant is a gas, such as nitrogen or an inert gas. Where a gas is used as the coolant, the temperature of an injected coolant stream can be relatively low due to the thermodynamic decrease in temperature as a gas is allowed to expand to a lower pressure. Here, the use of a highly conductive gas, such as an inert gas, enables expansion cooling of the injected coolant (gas) as it is injected at the coolant injection ports.

In one embodiment of the apparatus and system of the present invention, a secondary set of coolant injection ports may be provided within the drill head to provide additional protection of the interior wall of the debris removal passage of the drill head. For example, but not by way of limitation, a secondary set of coolant injection ports may be disposed at or near the mouth of the debris removal passage of the drill head, angularly distributed about the mouth, and directed to provide a protective layer of coolant along the initial portion of the interior wall of the debris removal passage. The secondary set of coolant injection ports prevent any melted formation components or debris that make it through the primary curtain provided by the primary set of coolant injection ports from adhering to the interior wall of the debris removal passage.

The number and the position of coolant injection ports, and the number and position of sweeping gas injection ports, may vary depending on the size, capacity and configuration of the drill head. Similarly, a drill head may comprise one or more debris removal passages, just as an umbilical to which the drill head is connected may comprise one or more debris removal channels. The debris removal passage may be central to the body, just as the debris removal channel may be central to the umbilical, or the debris removal passage may be asymmetrically located within the body and the debris removal channel may run along a side of the umbilical. In one embodiment, the debris removal channel may comprise a large, outer conduit through which the gas conduit, the optical fibers and the coolant conduit may pass. In another embodiment, the debris removal channel may comprise a reinforced conduit resistant to collapse by the differential pressure into the channel.

The umbilical, which is illustrated without a casing or outer protective sheath in FIG. 4 discussed below, may comprise an outer protective conduit through which the gas conduit, the optical fibers, the coolant conduit and the debris removal channel may all pass. The outer conduit may comprise an exterior comprising or conditioned with a lubricious material to facilitate the insertion and removal of the umbilical to and from an earthen bore system.

FIG. 1 is a schematic illustrating an aspect of the system 10 of the present invention. A borehole 90 is drilled into the earth's crust 11 so that a portion 17 of the borehole 90 penetrates a geologic formation 19 bearing a fluid medium such as, for example, hydrocarbons. The system 10 comprises a coiled tubing unit at the surface 15 having a source of pressurized gas 12 fluidically coupled through a gas leader 13 to a gas conduit (not shown) within an umbilical 34, a portable electric generator 14 electrically coupled through a power supply leader 18 to power a laser light generator 16 that is, in turn, optically coupled through a laser leader 26 to a plurality of optical fibers 47 (not shown in FIG. 1) within the umbilical 34. The system 10 of FIG. 1 further comprises a wellhead 25 sealing the surface end 91 of the borehole 90 through which the umbilical 34 is received into the borehole 90, a working fluid tank 20 coupled through a working fluid leader 22 to the wellhead 25 to enable the introduction and removal of working fluid 21 into and from an annulus 24 between the umbilical 34 and the wall 94 of the borehole 90. The system further comprises a spool 30 on which an extended length of umbilical 34 may be stored, and a coiled tubing unit guide support 27 to support an umbilical guide 38 having a plurality of rolling elements 37 therein to reduce friction of movement of the umbilical 34 into and from the wellhead 25 and the borehole 90. The system 10 and the coiled tubing unit thereof further comprise a drill head 50 connected at a connected end 36 to the umbilical 34 and positionable within the borehole 90 by letting out and reeling in the umbilical 34 from and onto the spool 30.

The system 10 comprises a spool 30 that is rotatable on an axle (not shown in FIG. 1) using a motor and related gears (not shown) to control the position of the drill head 50 by letting out and reeling in the umbilical 34 thereon. In FIG. 1, the spool 30 has been reeled out to provide sufficient umbilical 34 through the wellhead 25 to position the drill head 50 adjacent to a targeted portion of the wall to be extended 92, which is a small portion of the wall 94 of the borehole 90 that is adjacent the drill head 50. The drill head 50 comprises a deployable circumferential seal 54 that, upon deployment, seals the annulus between the exterior surface of the drill head 50 and the wall 94 of the borehole 90 in which the drill head 50 is positioned.

FIG. 2 is a perspective view of an alternative umbilical storage spool 32A that can be used to store an umbilical 34 of a system of the present invention by coiling the umbilical 34 against the interior wall 33 of the spool 32A. After a portion of the interior wall 33 is covered with outer coils 42 of the umbilical 34, additional, smaller coils can be disposed within the initial, outer coils 42 for additional storage capacity. FIG. 3 is a top view of a second alternative umbilical spool 32B that can be used to store an umbilical 34 of a system of the present invention by wrapping coils 44 around an exterior wall 41 of a center post 38 of the spool 34B. After a portion of the exterior wall 41 is covered with coils 44 of the umbilical 34, additional, larger coils can be disposed about the initial, inner coil 40 for additional storage capacity.

FIG. 4 is an enlarged perspective view of the drill head 50 of FIG. 1 that can be used to implement an aspect of the system of the present invention. The drill head 50 comprises a plurality of optical elements 45 optically coupled to a plurality of elongate optical fibers 47 that optically conduct laser light (not shown) provided from the laser light source 16 (not shown) through the laser leader 26 (not shown) to a surface end of the optical fibers 47 (not shown). The optical elements 45 in the drill head 50 are disposed in a generally concentric pattern within a leading end 56 of the drill head. The optical elements may be disposed in a number of various patterns or positions within the drill head 50.

The drill head of FIG. 4 further comprises at least one gas injection port 46 disposed within the leading end 56 of the drill head 50 and positioned to inject a gas (not shown) into a section of the bore to be extended using laser light (not shown) emitted from the optical elements 45 of the drill head 50. In the drill head 50 of FIG. 4, the gas injection port 46 is disposed generally interior to a concentric pattern of optical elements 45. The gas injection port 46 may alternately be disposed in a number of positions within the drill head 50 and the stream of gas injected into the bore section can be directed by positioning of the gas injection port 46 at a selected angle relative to an axis 62 of the drill head 50. The drill head 50 further comprises a debris removal passage (not shown) having a mouth 66 disposed to receive molten formation components and debris from a laser-heated portion of a bore wall (not shown).

The body or drill head 50 further comprises a deployable seal 54 around the exterior surface 59 of the body or drill head 50. The deployable seal 54 is illustrated in FIG. 4 in the deployed mode to seal an annulus (not shown) between the exterior surface 59 of the drill head 50 and the wall of a bore (not shown) in which the drill head 50 may be positioned to facilitate the isolation of the bore section to be extended from the remainder of the bore system.

For example, but not by way of limitation, the drill head 50 may be positioned within a portion of a bore to be conditioned thereby, the deployable seal 54 may be deployed to engage a wall of a portion of the bore to seal an annulus between the exterior surface 59 of the drill head 50 and the wall of the bore. Gas provided to the drill head through a gas conduit 49 within the umbilical 34 used to position the drill head 50 is injected into a portion of the bore proximal to the leading end 56 of the drill head 50 to displace laser obstructing materials, such as working fluid, drilling fluid, formation fluid or a mixture thereof, from the section of the bore. In the drill head 50 of FIG. 4, the displaced laser obstructing material, and the gas injected through the gas injection port 46 to displace the laser obstructing material, sweeps to the mouth 66 of the debris removal passage (not shown), through the debris removal passage and to the surface.

Some laser-obstructing materials may be displaced from the bore section through the debris removal passage (not shown) of the drill head 50, and some of the laser-obstructing materials may be displaced from the bore section to be extended by forced displacement past the deployable seal 54. It may be necessary to provide generally continuous gas injection through the gas injection port 46 to prevent working fluid or drilling fluid from re-entering the bore section at the deployable seal 54.

FIG. 5 is an enlarged partial section view the drill head 50 portion of one embodiment of the apparatus and system of the present invention that can be positioned within a bore 90 to extend the bore 90 within a geologic formation 19. The drill head 50 of FIG. 5 comprises a body 65 having an exterior surface 59, a deployable seal 54 around the body 65, a plurality of optical fibers 47 within the body 65 and optically coupled to optical elements 45 housed in a generally concentric pattern at a leading end 56 of the drill head 50 to irradiate the targeted wall portion 92 with laser light 52 upon activation. The drill head 50 of FIG. 5 further comprises a gas conduit 49 to provide gas to a gas injection ports 46 for introducing a gas to displace laser obstructing materials from a laser path 17 proximal the leading end 56 of the drill head 50. The drill head 50 of FIG. 5 further comprises a gas lateral 64 to receive gas from the gas conduit 49 upon opening of the seal gas valve 63 and to deliver the gas to the deployable seal 54 to deploy the seal to the sealing mode shown in FIG. 5. The drill head 50 of FIG. 5 further comprises a deflation stem 60 having a seal deflation valve 61 to relieve gas pressure within the deployable seal 54 to restore the deployable seal 54 to a retracted mode (not shown in FIG. 5). The drill head 50 further comprises a debris removal passage 67 having a mouth 66 disposed towards the targeted portion 92 of the bore wall 94. A plurality of coolant injection ports 68 are angularly distributed about the mouth 66 of the debris removal passage 67 and fluidically coupled to a coolant distribution manifold 69 supplied by a coolant supply line 70. Pressurized coolant is delivered through the coolant supply line 70 to the distribution manifold 69, and therein distributed to the plurality of coolant injection ports 68 from which coolant streams 71 are injected into the debris removal passage 67. The plurality of coolant streams 71 together form a curtain 74 that acts as a barrier to molten formation components and heated debris 81 from engaging the interior wall 76 of the debris removal passage 67 without first being frozen and cooled, respectively, upon contact with the coolant curtain 74.

As laser light 52 is transmitted through the optical fibers 47 to the optical elements 45 and impinged onto the targeted portion 92 of the bore wall 94, formation components 77 begin to melt. Melted formation components 77 are swept into motion by a gas stream 78 injected into the laser path 17 from the gas injection port 46. The pressure in the debris removal channel (not shown in FIG. 5) and in the debris removal passage 67 connected thereto is maintained below the pressure within the bore section to provide for gas flow from the bore section to the surface through the mouth 66, the debris removal passage 67 and the debris removal channel (not shown) of the umbilical. The gas stream 78 disturbs the laser path 17 and adjacent targeted portion 92 of the bore wall 94 and sweeps molten formation components and heated debris 81 into the mouth 66 of the debris removal passage 67. The molten formation components and heated debris 81 are drawn into the debris removal passage 67 and engage the curtain 74 of coolant comprised of the injected streams 71 from the coolant injection ports 68.

FIG. 6 illustrates an alternative arrangement of coolant injection ports that can be used to condition molten formation components and heated debris to prevent these materials from adhering to the interior wall of the debris removal passage 67 of the drill head (not shown in FIG. 6). The alternative arrangement illustrated in FIG. 6 comprises at least one primary coolant injection port 68 at the mouth 66 of the debris removal passage 67 to provide at least one stream of injected coolant 71. A plurality of primary coolant injection ports 68 may be angularly distributed about the mouth 66 to together provide a generally conical curtain or barrier of coolant (not shown in FIG. 6) to freeze and cool molten formation components and heated debris, respectively, entering the debris removal passage 67. The coolant streams 71 provided by a plurality of primary coolant injection ports 68 will be at an angle to the interior wall 76 of the debris removal passage 67. The alternative arrangement further comprises at least one secondary coolant injection port 85 at the mouth 66 of the debris removal passage 67 to provide a secondary stream 87 of injected coolant in a generally longitudinal direction along the interior wall 76 of the debris removal passage 67 that provides additional protection against adherence of molten formation components and heated debris to the interior wall 76 of the debris removal passage 67. A plurality of secondary coolant injection ports 85 may be angularly distributed about the mouth 66 to together provide a generally sleeve-like barrier to prevent adherence of molten formation components or heated debris that might penetrate the primary, conical curtain and remain molten or very hot. FIG. 6 illustrates only a single primary coolant injection port 71 and a single secondary coolant injection port 87 for simplicity and to illustrate the difference in the angle and purpose of the primary and secondary streams of injected coolant 71, 87.

In a preferred embodiment, the number of primary coolant injection ports 68 may be three or more, and the number of secondary coolant injection ports 85 may be three or more. The primary coolant injection ports 68 may, in one embodiment, be vertically aligned with the secondary coolant injection ports 85, or the primary and secondary coolant injection ports may be offset as illustrated in FIG. 6. The arrangement, locations, angle and number of primary and/or secondary coolant injection ports may be varied depending on the size of the debris removal passage 67 and the nature and composition of the formation components and debris to be removed therethrough.

Formation components, when melted using laser light, form globules due to viscoelastic forces acting at the surface. The apparatus and system of the present invention relies on disruption of these globules to condition melted formation components for being transported to the surface. FIG. 7 is an illustration of one mode of globule deformation that may occur as a globule 86 of molten formation components enters an accelerated gas stream (not shown) within the debris removal passage 67 in a drill head (not shown). Gas that has been introduced into the bore section through gas injection ports is removed from the bore section by the debris removal channel, and that the gas will necessarily accelerate as it nears the mouth 66 of the debris removal channel 67, which is maintained at a pressure lower than that in the bore section being extended using the drill head. As illustrated in FIG. 7, the accelerating gas stream surrounds the globule 86, or the globule's deformed remains 88, 89 and 93, as the globule 86 enters and then passes through the debris removal passage 67. The speed of the gas stream surrounding and deforming the globule 86 is indicated by the length of the arrows 95A, 95B, 95C and 95D adjacent to the globule 86 and the globule's remains 88, 89 and 93. As illustrated in FIG. 7, a globule 86 of molten formation components generated by a laser drilling process (not shown in FIG. 7) moves towards the mouth 66 of the debris removal passage 67 with a speed indicated by the length of arrow 95A due to the flow of a gas stream (not shown) surrounding the globule 86. As the speed of the surrounding gas stream increases as indicated by arrow 95B, the globule 88 begins to flatten and deform. As the speed of the surrounding gas stream increases further as indicated by arrow 95C, the globule 89 begins to break apart due to aerodynamic forces overcoming the viscoelastic forces tending to maintain the globule in a unitary structure. As the speed of the surrounding gas stream increases to a maximum speed 95D, the globule remnants 93 break apart and then encounter the coolant barrier (not shown) illustrated in FIG. 5.

FIG. 8 is a view of an alternative arrangement of coolant injection ports 68, secondary coolant injection ports 87, debris removal passage mouth 66 and optical elements 45 in an alternative embodiment of a body 50 that can be positioned using an umbilical (not shown) in an embodiment of a system and apparatus of the present invention.

A bore system may comprise a single bore without intersecting laterals or, alternately, a borehole system may comprise a primary bore having one or more interesting lateral bores. The apparatus and system of the present invention may be used to extend a section of a wall of a single bore without intersecting laterals, or to extend a section of a wall of a lateral bore that intersects a primary bore. Tools, such as guide tools and whipstocks, can be used to guide the drill head 50 of the system of the present invention into a lateral bore intersecting a primary bore in a bore system.

FIG. 9 is an elevation view of a portion of a borehole system comprising a lateral bore 72 intersecting a primary bore 90 at a window 84 in a casing 82 installed within the primary bore 90 and cemented into place using cement 80. The lateral bore 72 of FIG. 6 has an initial section 70 and a plurality of bends 73 indicating that the lateral bore 72 is bored using a tool steered to penetrate and drain formation fluid from a geologic formation 19.

FIG. 10 is an elevation view of the portion of a borehole system of FIG. 9 after a guide tool 98 is disposed in the primary bore 90 to guide the drill head 50 (not shown in FIG. 10) through the casing window 84 and into the lateral bore 72 to extend a portion of a wall 94 of the lateral bore 72 to better drain the adjacent geologic formation 19. The guide tool 98 has shoes 96 to grip the casing 82, and an inclined surface 97 thereon to deflect a drill head 50 (not shown in FIG. 10) into the window 84 milled in the casing 82 and the cement liner 80. The size, length and diameter of the drill head 50 (not shown) to be positioned in the lateral bore 72, an angle of the inclined surface 97, the configuration of the guide tool 98, the size of the window 84 and an angle of intersection 99 of the initial section 70 of the lateral bore 72 are among factors to be considered in extending a section of a wall 94 of a bore 72 in accordance with the present invention.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, a “set” may comprise a single member or a plurality of members. For example, a set of coolant injection ports or a set of gas injection ports may comprise a single coolant injection port or a single gas injection port or it may comprise a plurality of coolant injection ports or gas injection ports.

As used herein, the term “working fluid” refers to a fluid introduced into the bore system for the purpose of lubricating the bore system to facilitate the smooth insertion, positioning and removal of the apparatus comprising the drill head, for the purpose of hydrostatically opposing or balancing formation pressure to minimize the potential for well control problems due to an unwanted and unexpected influx of formation fluids into the bore.

As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, components and/or groups, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. The terms “preferably,” “preferred.” “prefer.” “optionally,” “may,” and similar terms are used to indicate that an item, condition or step being referred to is an optional (not required) feature of the invention.

The corresponding structures, materials, acts, and equivalents of all means or steps plus function elements in the claims below are intended to include any structure, material, or act for performing the function in combination with other claimed elements as specifically claimed. The description of the present invention has been presented for purposes of illustration and description, but it is not intended to be exhaustive or limited to the invention in the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the invention. The embodiment was chosen and described in order to best explain the principles of the invention and the practical application, and to enable others of ordinary skill in the art to understand the invention for various embodiments with various modifications as are suited to the particular use contemplated. 

We claim:
 1. A system comprising: an umbilical having an elongate gas conduit, an elongate coolant conduit, a debris removal channel and a plurality of elongate optical fibers; a body, connected at a proximal end to a leading end of the umbilical, and further comprising a distal end with an optical element to condition laser light emitted from a leading end of the plurality of optical fibers, a deployable circumferential seal between the proximal end and the distal end, a debris removal passage therethrough and coupled to a leading end of the debris removal channel, a gas port directed from the body and coupled to a leading end of the gas conduit, and a coolant port directed into the debris removal passage and coupled to a leading end of the coolant conduit; a pressurized gas source fluidically coupled to a surface end of the gas conduit, a coolant source fluidically coupled to a surface end of the coolant conduit; a laser light power generator optically coupled to a surface end of the plurality of optical fibers; and a debris receiver fluidically coupled to a surface end of the debris removal channel; wherein gas released into a portion of a bore section into which the body is positioned purges the bore section distal to the circumferential seal to clear a laser path forward of the distal end of the body; wherein gas released from the gas port into the bore section sweeps molten formation components from a laser-heated portion of the bore wall into the debris removal passage; and wherein coolant injected from the coolant port into the debris removal passage freezes molten debris components swept from the laser-heated portion of a bore wall to the debris removal passage for removal from the borehole through the debris removal channel.
 2. The system of claim 1 wherein the circumferential seal of the body is radially outwardly expandable from a retracted mode to an expanded mode to seal an annulus between the exterior of the body and a wall of a borehole in which the body is positioned.
 3. The system of claim 2 wherein the circumferential seal is pressure-expandable within a borehole using pressurized fluid from one of the gas conduit and the liquid conduit.
 4. The system of claim 3 wherein the umbilical further comprises: a seal deployment valve; and an elongate conductive member having a surface end and a leading end to deliver an activation signal to the seal deployment valve.
 5. The system of claim 1 wherein the pressurized gas is one of an inert gas, carbon dioxide and nitrogen.
 6. The system of claim 1 wherein the coolant is one of water, potassium chloride, deionized water, inhibited glycol and water solutions, and dielectric fluids.
 7. The system of claim 1 wherein the debris removal passage is generally central to the body.
 8. The system of claim 1 wherein an interior wall of the debris removal passage comprises one of aluminum, aluminum alloy, steel, steel alloy and ceramic.
 9. The system of claim 1 wherein the coolant injection port comprises: a plurality of coolant injection ports angularly distributed about an inlet to the debris removal passage to provide a generally convergent injection pattern to freeze entering molten debris.
 10. The system of claim 1 wherein the at least one gas injection port directed away from the body and coupled to a laser emitting end of the gas conduit comprises: a plurality of gas injection ports angularly distributed about the body and proximal to the laser emitting end of the body; wherein the plurality of gas injection ports are directed anterior to the laser emitting end of the body to sweep molten debris radially inwardly to the debris removal passage.
 11. The system of claim 1 wherein the debris receiver operates at a pressure that is substantially lower than the pressure at which liquid and gas is injected into the borehole to promote sweeping of debris produced by impingement of laser light on a portion of the wall of the borehole proximal to the laser emitting end of the body into the debris removal passage of the body.
 12. The system of claim 1 further comprising: a plurality of secondary coolant injection ports on the body to inject a stream of coolant directed generally longitudinally along the interior wall of the debris removal passage of the body.
 13. An apparatus comprising: a body having a debris removal passage therethrough, an emitting end with an optical laser light focusing element, a connected end opposite the emitting end, and a radially outwardly deployable circumferential seal therebetween; and an umbilical having a gas conduit connected to supply pressurized gas to a plurality of angularly-distributed gas injection ports on the body, a coolant conduit connected to supply coolant to a plurality of angularly-distributed coolant injection ports on the body, a plurality of optical fibers connected to supply laser light to the optical laser light focusing element, and a debris removal channel connected to remove conditioned debris received from a bore section through the debris removal passage of the body; wherein deployment of the deployable seal with the body positioned within a bore section enables a portion of the bore section adjacent to the emitting end of the body to be isolated from a portion of the bore section adjacent to the umbilical; wherein the gas injection ports of the body are directed to sweep melted formation components from a laser-heated portion of a bore wall generally opposite a laser path from the emitting end of the body; and wherein the coolant injection ports of the body are directed to provide a radially-convergent injection pattern to freeze molten debris swept into the debris removal passage of the body.
 14. The apparatus of claim 13 wherein the circumferential seal of the body is radially outwardly expandable upon deployment from a retracted mode to an expanded mode to provide a seal between the exterior of the body and a wall of a bore section in which the body may be disposed.
 15. The apparatus of claim 14 wherein the circumferential seal is selectively deployable using pressurized fluid provided to the body by one of the gas conduit and the coolant conduit.
 16. The apparatus of claim 13 wherein the umbilical further comprises: a seal deployment valve; and an elongate conductive member to deliver an activation signal to the seal deployment valve.
 17. The apparatus of claim 13 wherein the pressurized gas is one of an inert gas, carbon dioxide and nitrogen.
 18. The apparatus of claim 13 wherein the coolant is one of water, potassium chloride, deionized water, inhibited glycol and water solution, and dielectric fluid.
 19. The apparatus of claim 13 wherein the debris removal passage is generally central to the body.
 20. The apparatus of claim 13 wherein the interior wall of the debris removal channel comprises at least one of aluminum, an aluminum alloy, steel, a steel alloy and ceramic.
 21. The apparatus of claim 13 wherein the plurality of angularly-distributed coolant injection ports on the body are directed to a center of a debris removal passage of the body coupled to a leading end of the debris removal channel of the umbilical; and wherein the plurality of coolant injection ports provide a generally convergent injection pattern of coolant to freeze molten debris entering the debris removal passage of the body.
 22. The apparatus of claim 13 wherein the gas conduit connected to supply pressurized gas to a plurality of angularly-distributed gas injection ports on the body comprises: a plurality of gas injection ports angularly distributed about the body and disposed proximal to the emitting end of the body; wherein the plurality of gas injection ports provide a gas stream directed anterior to the emitting end of the body to sweep molten debris radially inwardly to a throat of the debris removal passage of the body.
 23. The apparatus of claim 13 further comprising: a debris receiver coupled to a surface end of the debris removal channel of the umbilical and operable at a pressure substantially less than the pressure at which gas is injected into the bore section to sweep molten formation components into the debris removal passage of the body.
 24. The apparatus of claim 13 further comprising: a plurality of secondary coolant injection ports on the body to inject a stream of coolant directed generally longitudinally along the interior wall of the debris removal passage of the body. 